Graco Gmax 7900 User manual

Instructions
G-Max®7900 Airless
Paint Sprayer 308870G
EN
For Portable Airless Spraying of Architectural Coatings and Paints.
3300 psi (227 bar, 22.7 MPa) Maximum Working Pressure
Models
NOTE: All models are not available in all countries.
Related Manuals
Model Series Description
232630 B Hi-Boy
232631 BHi-Boy with RAC 5 tip, gun and hose
232632 B Lo-Boy
232633 BLo-Boy with RAC 5 tip, gun and hose
233008 A Hi-Boy with Gauge Kit
Important Safety Instructions
Read all warnings and instructions in this
manual. Save these instructions.
Manual Manual Number
Operation 308867
Displacement Pump 307898
Spray Gun 309091
Spray Tip 309055
PC Board 308919
Drain Valve Kit 308961

Table of Contents
2308870G
Table of Contents
Warnings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Component Identification . . . . . . . . . . . . . . . . . . . . 5
Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Pressure Relief Procedure . . . . . . . . . . . . . . . . . 6
Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Pinion Assembly / Rotor / Field / Shaft / Clutch . 13
Clamp . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Engine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
On / Off Switch . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Pressure Control . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Control Board . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Pressure Control Transducer . . . . . . . . . . . . . . 19
Pressure Adjust Potentiometer . . . . . . . . . . . . . 20
Control Board Diagnostics . . . . . . . . . . . . . . . . 21
Displacement Pump . . . . . . . . . . . . . . . . . . . . . . . 22
Pump Pin Clip . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Parts List & Drawing - Pinion Assembly . . . . . . . 24
Parts Drawing - Hi-Boy Sprayer . . . . . . . . . . . . . . 25
Model 232630 and 233008 . . . . . . . . . . . . . . . . 25
Parts List - Hi-Boy Sprayers . . . . . . . . . . . . . . . . . 26
Models 232630, 232631 and 233008* . . . . . . . 26
Parts Drawing - Lo-Boy Sprayer . . . . . . . . . . . . . 28
Model 232632, 232633 . . . . . . . . . . . . . . . . . . . 28
Parts List - Lo-Boy Sprayers . . . . . . . . . . . . . . . . 29
Models 232632, 232633 . . . . . . . . . . . . . . . . . . 29
Model 232630 through 232633 . . . . . . . . . . . . . 31
Parts List - Hi-Boy Sprayers . . . . . . . . . . . . . . . . . 32
Models 232630 through 232633 . . . . . . . . . . . . 32
Parts List - Complete Sprayers . . . . . . . . . . . . . . 33
Models 232631, 232633 . . . . . . . . . . . . . . . . . . 33
Displacement Pump Repair Kit . . . . . . . . . . . . . 33
Danger Labels . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Wiring Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Technical Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Model 232630, 232631, 232008 . . . . . . . . . . . . 35
Model 232632, 232633 . . . . . . . . . . . . . . . . . . . 35
Graco Warranty . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

Warnings
308870G 3
Warnings
The following warnings are for the setup, use, grounding, maintenance, and repair of this equipment. The exclama-
tion point symbol alerts you to a general warning and the hazard symbols refer to procedure-specific risks. When
these symbols appear in the body of this manual or on warning labels, refer back to these Warnings. Product-specific
hazard symbols and warnings not covered in this section may appear throughout the body of this manual where
applicable.
WARNING
FIRE AND EXPLOSION HAZARD
Flammable fumes, such as solvent and paint fumes, in work area can ignite or explode. To help prevent
fire and explosion:
• Use equipment only in well ventilated area.
• Do not fill fuel tank while engine is running or hot; shut off engine and let it cool. Fuel is flammable
and can ignite or explode if spilled on hot surface.
• Eliminate all ignition sources; such as pilot lights, cigarettes, portable electric lamps, and plastic drop
cloths (potential static arc).
• Keep work area free of debris, including solvent, rags and gasoline.
• Do not plug or unplug power cords, or turn power or light switches on or off when flammable fumes
are present.
• Ground all equipment in the work area. See Grounding instructions.
• Use only grounded hoses.
• Hold gun firmly to side of grounded pail when triggering into pail. Do not use pail liners unless they
are antistatic or conductive.
•Stop operation immediately if static sparking occurs or you feel a shock.Do not use equipment
until you identify and correct the problem.
• Keep a working fire extinguisher in the work area.
SKIN INJECTION HAZARD
High-pressure spray is able to inject toxins into the body and cause serious bodily injury. In the event
that injection occurs, get immediate surgical treatment.
• Do not aim the gun at, or spray any person or animal.
• Keep hands and other body parts away from the discharge. For example, do not try to stop leaks
with any part of the body.
• Always use the nozzle tip guard. Do not spray without nozzle tip guard in place.
• Use Graco nozzle tips.
• Use caution when cleaning and changing nozzle tips. In the case where the nozzle tip clogs while
spraying, follow the Pressure Relief Procedure for turning off the unit and relieving the pressure
before removing the nozzle tip to clean.
• Do not leave the unit energized or under pressure while unattended. When the unit is not in use, turn
off the unit and follow the Pressure Relief Procedure for turning off the unit.
• Check hoses and parts for signs of damage. Replace any damaged hoses or parts.
• This system is capable of producing 3000 psi (210 bar/21 MPa). Use Graco replacement parts or
accessories that are rated a minimum of 3000 psi (210 bar/21 MPa).
• Always engage the trigger lock when not spraying. Verify the trigger lock is functioning properly.
• Verify that all connections are secure before operating the unit.
• Know how to stop the unit and bleed pressure quickly. Be thoroughly familiar with the controls.

Warnings
4308870G
EQUIPMENT MISUSE HAZARD
Misuse can cause death or serious injury.
• Do not operate the unit when fatigued or under the influence of drugs or alcohol.
• Do not exceed the maximum working pressure or temperature rating of the lowest rated system
component. See Technical Data in all equipment manuals.
• Use fluids and solvents that are compatible with equipment wetted parts. See Technical Data in all
equipment manuals. Read fluid and solvent manufacturer’s warnings. For complete information
about your material, request MSDS from distributor or retailer.
• Do not leave the work area while equipment is energized or under pressure. (
• Turn off all equipment and follow the Pressure Relief Procedure when equipment is not in use.
• Check equipment daily. Repair or replace worn or damaged parts immediately with genuine manu-
facturer’s replacement parts only.
• Do not alter or modify equipment. Alterations or modifications may void agency approvals and create
safety hazards.
• Make sure all equipment is rated and approved for the environment in which you are using it.
• Use equipment only for its intended purpose. Call your distributor for information.
• Route hoses and cables away from traffic areas, sharp edges, moving parts, and hot surfaces.
• Do not kink or over bend hoses or use hoses to pull equipment.
• Keep children and animals away from work area.
• Comply with all applicable safety regulations.
PERSONAL PROTECTIVE EQUIPMENT
Wear appropriate protective equipment when in the work area to help prevent serious injury, including
eye injury, hearing loss, inhalation of toxic fumes, and burns. This protective equipment includes but is
not limited to:
• Protective eyewear, and hearing protection.
• Respirators, protective clothing, and gloves as recommended by the fluid and solvent manufacturer
WARNING

Component Identification
308870G 5
Component Identification
*For more detailed explanations of these controls, refer to the Honda Engines Owner's Manual; supplied.
APressure Control Switch ON/OFF, enables/disables clutch function and pressure control
BPressure Adjusting Knob Controls fluid outlet pressure
CAir Cleaner* Filters air entering the carburetor
DFuel Tank* Uses 86 octane unleaded gasoline
EMuffler* Reduces noise of internal combustion
FSpark Plug Cable* Routes electrical current to spark plug
GFuel Shutoff Lever* On/off lever to regulate fuel flow from gasoline tank to carburetor
HChoke* Enriches air/gasoline mixture for cold starting
JThrottle Lever* Adjusts engine speed for large or small orifice spray tips
KEngine Switch* Enables/disables engine operation
LSecondary Fluid Outlet Second hose and spray gun is connected here
MPressure Control Controls clutch cycling to maintain fluid pressure
NPrimary Fluid Outlet Hose and spray gun is connected here
PEngine* 4-cycle gasoline engine
RClutch Housing Transfers power from engine to drive assembly
SDrive Housing Transfers power from clutch to displacement pump
TDisplacement Pump Provides fluid to be sprayed through spray gun
UFluid Filter Filters fluid between source and spray gun
VGrounding Clamp and Wire Grounds sprayer system
WPail Hanger Provides a hanger for paint pail
XDrain Valve Relieves fluid pressure when open
S
U
W
T
X
V
P
AB
C
E
F
G
H
J
K
202 Main hose
203 Whip end hose
204 Contractor gun with RAC 5
DripLess tip guard and 517 size SwitchTip
203
204
202
M
N
L
Model 232631
R
D
9034B

Maintenance
6308870G
Maintenance
NOTE: For detailed engine maintenance and specifica-
tions, refer to separate Honda Engines Owner's Manual,
supplied.
Pressure Relief Procedure
Follow the Pressure Relief Procedure whenever
you see this symbol.
1. Engage trigger lock.
2. Turn ON/OFF switch to OFF.
3. Move pressure control switch to OFF and turn pres-
sure control knob fully counterclockwise.
4. Unlock trigger safety. Hold metal part of gun firmly
to side of grounded metal pail, and trigger gun to
relieve pressure.
5. Lock gun trigger safety.
6. Open the pressure drain valve. Leave the pressure
drain valve open until you are ready to spray again.
7. If you suspect the spray tip or hose is clogged or
that pressure has not been fully relieved after follow-
ing the steps above, VERY SLOWLY loosen tip
guard retaining nut or hose end coupling to relieve
pressure gradually, then loosen completely. Clear
hose or tip obstruction.
Maintenance Checklist
•DAILY: Check engine oil level and fill as necessary.
•DAILY: Check hose for wear and damage.
•DAILY: Check gun safety for proper operation.
•DAILY: Check pressure drain valve for proper oper-
ation.
•DAILY: Check and fill the gas tank.
AFTER THE FIRST 20 HOURS OF OPERATION:
• Drain engine oil and refill with clean oil. Reference
Honda Engines Owner's Manual for correct oil vis-
cosity.
•WEEKLY: Remove air filter cover and clean ele-
ment. Replace element, if necessary. If operating in
an unusually dusty environment: check filter daily
and replace, if necessary.
Replacement elements can be purchased from your
local HONDA dealer.
•WEEKLY: Check level of TSL in displacement
pump packing nut. Fill nut, if necessary. Keep TSL
in nut to help prevent fluid buildup on piston rod and
premature wear of packings.
AFTER EACH 100 HOURS OF OPERATION:
• Change engine oil. Reference Honda Engines
Owner's Manual for correct oil viscosity.
SPARK PLUG:
• Use only BPR6ES (NGK) or W20EPR-U (NIPPON-
DENSO) plug. Gap plug to 0.028 to 0.031 in. (0.7 to
0.8 mm).
• Use spark plug wrench when installing and remov-
ing plug.
This equipment stays pressurized until pressure is
manually relieved. To help prevent serious injury
from pressurized fluid, such as skin injection,
splashing fluid and moving parts, follow the Pressure
Relief Procedure when you stop spraying and before
cleaning, checking, or servicing the equipment.

Troubleshooting
308870G 7
Troubleshooting
Problem Cause Solution
Engine won't start Engine switch is OFF Turn engine switch ON
Engine is out of gas Refill gas tank. Honda Engines
Owner's Manual.
Engine oil level is low Try to start engine. Replenish oil, if
necessary. Honda Engines Owner's
Manual.
Spark plug cable is disconnected or
damaged
Connect spark plug cable or replace
spark plug
Cold engine Use choke
Fuel shutoff lever is OFF Move lever to ON position
Oil is seeping into combustion
chamber
Remove spark plug. Pull starter
rope 3 or 4 times. Clean or replace
spark plug. Try to start engine.
Keep sprayer upright to avoid oil
seepage.
Engine operates, but displacement
pump does not operate
Pressure control switch is OFF Turn pressure control switch ON.
Pressure setting is too low Turn pressure adjusting knob clock-
wise to increase pressure
Fluid filter (318) is dirty Clean filter. Page 31.
Tip or tip filter is clogged Clean tip or tip filter. Manual
309091.
Displacement pump piston rod is
stuck due to dried paint
Repair pump. Manual 308798.
Roller bearings are worn or dam-
aged
Replace connecting rod. Page 10.
Drive housing is worn or damaged Replace drive housing. Page 10.

Troubleshooting
8308870G
Engine operates, but displacement
pump does not operate (continued)
Electrical power is not energizing
clutch field
Check wiring connections. Page 15.
Reference control board diagnos-
tics. Page 21.
With pressure control switch ON
and pressure turned to MAXIMUM,
use a test light to check for power
between clutch terminals on control
board.
Remove black clutch wires from
control board and measure resis-
tance across wires. At 70_ F, the
resistance must be between 1.7
+0.2W; if not, replace clutch coil
241121.
Have pressure control checked by
authorized Graco dealer.
Clutch is worn or damaged Replace clutch. Page 13.
Pinion assembly is worn or dam-
aged
Repair or replace pinion assembly.
Page 13.
Pump output is low Strainer (31) is clogged Clean strainer
Piston ball (25) is not seating Service piston ball. Manual 308798.
Piston packings are worn or dam-
aged
Replace packings. Manual 308798.
O-ring (227) in displacement pump
is worn or damaged
Replace o-ring. Manual 308798.
Intake valve ball is not seating prop-
erly
Clean intake valve. manual 308798.
Engine speed is too low Increase throttle setting. Manual
308867.
Clutch is worn or damaged Replace clutch. Page 13.
Pressure setting is too low Increase pressure. Manual 308867.
Fluid filter (318), tip filter or tip is
clogged or dirty
Clean filter. Manual 308867 or
309091.
Large pressure drop in hose with
heavy materials
Use larger diameter hose and/or
reduce overall length of hose. Use
of more than 100 ft of 1/4 in. hose
significantly reduces performance of
sprayer. Use 3/8 in. hose for opti-
mum performance (50 ft minimum).
Problem Cause Solution

Troubleshooting
308870G 9
Excessive paint leakage into throat
packing nut
Throat packing nut is loose Remove throat packing nut spacer.
Tighten throat packing nut just
enough to stop leakage.
Throat packings are worn or dam-
aged
Replace packings. Manual 308798.
Displacement rod is worn or dam-
aged
Replace rod. Manual 308798.
Fluid is spitting from gun Air in pump or hose Check and tighten all fluid connec-
tions. Reprime pump. Manual
308867.
Tip is partially clogged Clear tip. Manual 309091.
Fluid supply is low or empty Refill fluid supply. Prime pump.
Manual 308867. Check fluid supply
often to prevent running pump dry.
Pump is difficult to prime Air in pump or hose Check and tighten all fluid connec-
tions.
Reduce engine speed and cycle
pump as slowly as possible during
priming.
Intake valve is leaking Clean intake valve. Be sure ball
seat is not nicked or worn and that
ball seats well. Reassemble valve.
Pump packings are worn Replace pump packings. Manual
308798.
Paint is too thick Thin the paint according to the sup-
plier's recommendations.
Engine speed is too high Decrease throttle setting before
priming pump. Manual 308867.
Clutch squeaks each time clutch
engages
Clutch surfaces are not matched to
each other when new and may
cause noise
Clutch surfaces need to wear into
each other. Noise will dissipate after
a day of run time.
Engine stalls Engine speed is to slow - Increase throttle setting.
- Adjust engine speed at no load to
3750 - 3850 rpm
Fluid filter is clogged Relieve pressure and clean filter
Too much pump friction (new pump) Reduce pressure to 3000 psi (20.68
MPa, 206.8 bar) until pump wears in
Spark plug wire is loose Reconnect wire
Problem Cause Solution

Rollers
10 308870G
Rollers
Removal
1. Relieve pressure, page 6.
2. Remove six cap screws (10) lock washers (9) and
cover assembly (24) (FIG. 1).
NOTE: A screw driver may be needed to pry off
cover assembly.
3. Remove dowel pins (97) and rollers (98).
Installation
1. Install rollers (98) and dowel pins (97).
2. Install cover assembly (24) with six lock washers (9)
and cap screws (10).
Drive Housing
Removal
1. Relieve pressure, page 6.
2. Remove six cap screws (10) lock washers (9) and
cover assembly (24) (FIG. 1).
3. Remove two screws (99) and washers (9).
4. Remove four cap screws (10) lock washers (9) from
drive housing (20).
5. Lightly tap around drive housing (20) to loosen drive
housing. Pull drive housing straight off pinion hous-
ing. Be prepared to support gear cluster (18), which
may also come out.
FIG. 1
9033A
10
9
97
98
20
9
99
24
FIG. 2
20
9
99
9
10
20h
20g
18
82
83
B
1
1Apply remaining grease to these areas